The impact of socioeconomic status (SES) on cognitive outcomes following radiotherapy for pediatric brain tumors: a prospective, longitudinal trial

Background: Socioeconomic status (SES) is a determinant of cognitive and academic functioning among healthy and ill children; however, few pediatric oncology studies examine SES and long-term cognitive functioning. The current study systematically investigated SES as a predictor of cognitive outcomes among children treated for localized brain tumors (BT) with photon radiation therapy (RT).

Methods: 248 children treated on a prospective, longitudinal, phase II trial of conformal RT (54-59.4 Gy) for ependymoma, low-grade glioma, or craniopharyngioma were monitored serially with cognitive assessments (intelligence quotient [IQ], reading, math, attention, adaptive function) for 10 years (2209 observations, median age at RT = 6.6 years, 48% male, 80% Caucasian). SES was derived from the Barratt Simplified Measure of Social Status, which incorporates parental occupation, education, and marital status.

Results: Overall, SES scores fell in the low range (Barratt median = 37). At pre-RT baseline, linear mixed models revealed significant associations between SES and IQ, reading, math, attention, and adaptive function, with higher SES associated with better performance (P < .005). SES predicted change over time in IQ, reading, and math; higher SES was associated with less decline (P < .001). Accounting for sex and age at RT, SES remained predictive of IQ, reading, and math. Analysis of variance revealed a greater relative contribution of SES than sex or age at RT to reading and math.

Conclusions: SES represents a novel predictor of cognitive performance before and after RT for pediatric BT. These findings have broad implications as high SES represents a protective factor. Developing interventions to mitigate the effects of low SES is warranted.